TRANSISTOR CE CHARACTERSTICS - Code

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Wednesday, October 5, 2011

TRANSISTOR CE CHARACTERSTICS


 TRANSISTOR CE CHARACTERSTICS
AIM:  1. To draw the input and output characteristics of transistor connected in  
              CE configuration
          2. To find β of the given transistor.
APPARATUS:
                           Transistor (BC 107)                       
                           R.P.S (O-30V)                     2Nos
                           Voltmeters (0-20V)              2Nos
                           Ammeters (0-200μA)          
                           (0-500mA)                            
                           Resistors     1Kohm            
                           Bread board
THEORY:
                 A transistor is a three terminal device. The terminals are emitter, base, collector. In common emitter configuration, input voltage is applied between base and emitter terminals and out put is taken across the collector and emitter terminals.
Therefore the emitter terminal is common to both input and output.
                The input characteristics resemble that of a forward biased diode curve. This is expected since the Base-Emitter junction of the transistor is forward biased. As compared to CB arrangement IB increases less rapidly with VBE . Therefore input resistance of CE circuit is higher than that of CB circuit.
                The output characteristics are drawn between Ic and VCE at constant IB. the collector current varies with VCE unto few volts only. After this the collector current becomes almost constant, and independent of VCE. The value of VCE up to which the collector current changes with V CE is known as Knee voltage. The transistor always operated in the region above Knee voltage, IC  is always constant and is approximately equal to IB.
     The current amplification factor of CE configuration is given by
                                         Β = ΔIC/ΔIB
CIRCUIT DIAGRAM:

PROCEDURE:

 INPUT CHARECTERSTICS:
1.    Connect the circuit as per the circuit diagram.
2.    For plotting the input characteristics the output voltage VCE is kept constant at 1V and for different values of VBE . Note down the values of IC
3.    Repeat the above step by keeping VCE at 2V and 4V.
4.    Tabulate all the readings.
5.    plot  the  graph between VBE and IB  for constant  VCE

OUTPUT CHARACTERSTICS:
1.    Connect the circuit as per the circuit diagram
2.    for  plotting the output characteristics  the input current  IB  is kept constant at 10μA and for different values of  VCE note down the values of IC 
3.    repeat the above step by keeping IB at 75 μA 100 μA
4.    tabulate the all the readings
5.    plot the graph between VCE and IC for constant IB




OBSERVATIONS:

INPUT CHARACTERISTICS:

S.NO
VCE = 1V
VCE = 2V
VCE = 4V
VBE(V)
IB(μA)
VBE(V)
IB(μA)
VBE(V)
IB(μA)








OUT PUT CHAREACTARISTICS:

S.NO
IB = 50 μA
IB = 75 μA
IB = 100 μA
VCE(V)
IC(mA)
VCE(V)
ICmA)
VCE(V)
IC(mA)







 








MODEL GRAPHS:
INPUT CHARACTERSTICS:



OUTPUT CHARECTERSTICS:



PRECAUTIONS:
       1. The supply voltage should not exceed the rating of the transistor
       2. Meters should be connected properly according to their polarities

RESULT:
  1. the input and out put characteristics of a transistor in CE configuration are Drawn
  2. the  of a given transistor is calculated 

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